No, they are not blind. If you are referring to them swimming to the surfance then diving down so fast the hit the bottom, this is a defensive tactice that ADFs use. in the wild they need to fear predators, they can more easily hide from predators at the bottom among the plants and rocks. Therefore, they go up, grab some air and go full speed back to the bottom where they are safe. They are also primarily nocturnal, so probably see better when it's dark.
My ADFs seem to see just fine. Though they have a better sense of smell. When I put food in the tank, they are usually hiding behind the rocks near the back of the tank. Within minutes they are all out coming for their dinner.
\Dan